Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only declare readOnlyHint and openWorldHint, so the description carries the rest and delivers: per-call cost (10 credits), the credit savings vs. alternatives, and a non-obvious behavioral constraint that the health score is unavailable for lat+lon-only searches. It also gives score interpretation bands (0–30 Calme … 81–100 Très actif), which meaningfully describe output behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the one-line purpose, then organized into required/optional/returns sections with clear headers. Slightly long with some restatement (the health requirement appears twice), but every block is scannable and useful given no output schema exists.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description fully documents the return shape (stats, trend, health components), the location-filter requirements, the health limitation, cost, and score interpretation. Nothing an agent needs to invoke or interpret the result is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, so the baseline is 3, but the description adds real semantics beyond the schema: it notes commune must be uppercase with the 'PARIS 01'–'PARIS 20' convention, gives concrete examples per filter, and crucially states that health requires code_postal/commune/code_departement (not lat+lon). That cross-parameter constraint is not derivable from the schema alone.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb, resource, and scope: 'Get a complete market brief for a location in one call — stats + trend + health score.' It explicitly distinguishes itself from siblings by naming the three tools it consolidates (analyze_market_statistics, analyze_price_trends, score_market_health). An agent can route to it without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use ('first tool for any "how is the market in X?" question') plus named alternatives it replaces and the cost rationale (saves 15–25 credits). This is the strongest form of routing guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.